- Overview
Shar Pei fever is an inherited auto-inflammatory disease that has been reported to occur in up to 23% of Shar Peis.
The disease tends to present as episodic bouts of fever that usually begin before 18 months of age, although adult-onset episodes may be seen.
Other signs may accompany the fever, such as swelling of the joints (most commonly the hock joint). Around half of affected dogs will experience hock swelling. Other less common signs include a swollen, painful muzzle, reluctance to ambulate, abdominal discomfort and GI distress, which arise as a result of systemic pain and inflammation.
The fever tends to be self-limiting, and usually resolves spontaneously over a period of 12 to 36 hours without treatment. Treatment is usually supportive as indicated, and includes NSAIDs or steroids to reduce pain and inflammation, and fluid therapy to maintain hydration.
- Why Does It Occur?
The heavily wrinkled and folded skin phenotype of Shar Peis is caused by a genetic mutation that causes an over-production of hyaluronic acid in the upper dermis of the skin. Hyaluronic acid makes up the intercellular matrix or scaffolding between cells, and helps to increase intracellular volume by binding large amounts of water molecules. This gives the breed their characteristic apperance.
However, the fragmentation of hyaluronic acid into low molecular-weight products serves as a self-trigger for the innate immune system, which result in a chronic state of inflammation in the breed.
This chronic state of inflammation is the basis for the recurrent bouts of fever and other complications seen in affected individuals.
- Renal Amyloidosis as a Complication
Chronic inflammation results in increased circulating levels of acute-phase proteins, such as serum amyloid A. This predisposes the breed to developing renal amyloidosis, which is the main complication seen with the disease.
AA amyloid is a by-product of serum amyloid A breakdown. In excess, it is unable to be excreted appropriately, and ends up being deposited into various organs in the body. In Shar Peis, the main target organ for deposition is the kidney, with amyloid deposition tending to occur mainly in the renal medulla. Once amyloid is deposited in tissue parenchyma, it causes a progressive and irreversible dysfunction of the kidney.
The disease can mimic signs of chronc kidney disease, with animals frequently presenting with signs such as vomiting, anorexia, lethargy, PU/PD, weight loss and dehydration. Unfortunately, by the time clinical signs are noticeable and amyloidosis is suspected, there will often already have been significant amyloid deposition and kidney damage, and the prognosis is poor.
No specific therapy has been proven to be beneficial in the treatment of renal amyloidosis in dogs. Colchicine is an anti-inflammatory that impairs the synthesis and secretion of serum amyloid A. It is understood that this helps prevent or reduce subsequent amyloid deposition in organs.
While its use in Shar Peis is unproven due to the lack of any prospective, placebo-controlled studies, the drug is used extensively in humans that are predisposed to developing renal amyloidosis. Colchicine (0.03 mg/kg/day) may be beneficial in minimizing the risk of developing systemic amyloidosis in Shar Peis suffering from Shar Pei fever.
